Differential association of free, conjugated, and bound forms of polyamines and transcript abundance of their biosynthetic and catabolic genes during drought/salinity stress in tomato (Solanum lycopersicum L.) leaves

Authors: UPADHYAY, REKESH - Purdue University; FATIMA, TAHIRA - Purdue University; HANDA, AVTAR - Purdue University; Mattoo, Autar

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2021
Publication Date: 10/15/2021
Citation: Upadhyay, R.K., Fatima, T., Handa, A.K., Mattoo, A.K. 2021. Differential association of free, conjugated, and bound forms of polyamines and transcript abundance of their biosynthetic and catabolic genes during drought/salinity stress in tomato (Solanum lycopersicum L.) leaves. Frontiers in Plant Science. 12:743568. https://doi.org/10.3389/fpls.2021.743568.
DOI: https://doi.org/10.3389/fpls.2021.743568

Interpretive Summary: Drought and salt stress are two severe stress conditions that impact crop productivity at global scale. Therefore, developing resilient crop germplasm that can withstand abiotic stress and anticipated impacts from climate change is necessitated. Polyamines are cellular metabolites that regulate a myriad of processes including seed germination, plant growth, development, senescence, abiotic stress, fruit development and ripening. In this study we studied the effects of polyamines in combating drought and salt stress in tomato tissue. A genomics approach was adopted to discern key genes involved in the synthesis of polyamines and how they are affected by the two stress conditions. We have thus identified the target genes that could help in developing plants that are resilient against drought and salt stress. These studies advance science and provide novel information on plant abiotic stress in datasets that can also help the scientific community. This research is important to scientists, biologists, geneticists, farmers, and industry.

Technical Abstract: Polyamines (PAs) have been implicated in ameliorating detrimental effects of drought and saline conditions on plant growth and development. The independent impact of these two abiotic stresses on polyamine biosynthesis, catabolism and homeostasis as well as on their transcript abundance in tomato leaves is presented here. We show here that the total levels of putrescine (Put), spermidine (Spd) and spermine (Spm) increase up to 72 h during drought and up to 48 h during salinity stress before their precipitable drop thereafter, indicating that tomato plants maintain survivability to drought as well as salinity stresses up to 3 d and 2 d, respectively. Multivariant analyses of stress kinetic data showed association of SPD-free and SPM-conjugate with both stresses, SPD-conjugate, SPM-bound, and SPM-conjugate forms with drought stress and PUT-conjugate and SPM-free with salinity stress. PAs biosynthesis genes, ARG1, SPDS1 and SAMDc3, segregated with drought and SPDS2 with salinity stress. PA catabolic enzymes CuAO4-like and PAO4 were associated with drought and salinity stresses, respectively, suggesting differential involvement of PAs biosynthesis and catabolic genes with drought and salinity stresses. Pearson correlation indicated that mostly positive correlations existed between the levels of free, conjugate and bound forms of Put, Spd and Spm under drought and salinity stress. However, mostly negative correlations were obtained between levels of various forms of the PAs and their biosynthesis and catabolic genes, Levels of different PA forms exhibited 2-fold higher negative correlation during drought stress as compared to salinity stress (66 vs 32) and with transcript levels of PA biosynthesis and catabolic genes. Transcripts of light-harvesting chlorophyll a/b-binding genes were generally positively associated with different forms of PAs but negatively to carbon flow genes. Most of the PA biosynthesis genes exhibited coordinate regulation under both stresses. Collectively, these results show that PAs are distinctly regulated under drought and salinity stresses with different and specific homologues of PA biosynthesis and catabolic genes contributing to accumulation of free, conjugated and bound forms of PAs.